1. Field of the Invention
The present invention pertains to fastening devices. More specifically, the present invention pertains to shackle type fastening devices and safety arrangements therefor.
2. Description of the Prior Art
A shackle is a U-shaped fastening device secured by a bolt or pin through holes in the end of the two arms of the U-shaped member. If a bolt is used, the bolt is typically threaded for engagement with corresponding threads in one of the arm holes or with a separate nut. In use, the bolt or pin is at least partially disengaged from the arm holes to allow insertion of another connecting member into the space between the arms. Then the bolt or pin is fully engaged to secure the connection. Such shackle arrangements are typically used to connect chains, cables, ropes, etc. to various loads and/or other connecting members.
Shackles are frequently used in heavy lifting with cranes, hoists, etc., especially in heavy construction or similar uses. Thus, it is very important that the shackle pin or bolt remain fully engaged to prevent accidental dropping of loads or severing of other connections. Due to the rather course threads associated with shackle bolts, such bolts may be easily backed off or unthreaded, unfastening such a connection and resulting in accidental property damage or, more importantly, bodily injury or death to people nearby. For this reason, the shackle bolt or pin is typically secured by a wire to prevent its disengagement. Such wiring is time consuming and fraught with danger if the wire is not properly secured or if it is not strong enough or if it has been used and bent to such an extent that the wire fails from fatigue. Obviously, safer means of retaining the shackle bolt are needed.